Method of Making a Combustion Turbine Component from Metallic Combustion Turbine Subcomponent Greenbodies

ABSTRACT

A method of making a combustion turbine component includes assembling a plurality of metallic combustion turbine subcomponent greenbodies together to form a metallic greenbody assembly and sintering the metallic greenbody assembly to thereby form the combustion turbine component. Each of the plurality of metallic combustion turbine subcomponent greenbodies may be formed by direct metal fabrication (DMF). In addition, each of plurality of metallic combustion turbine subcomponent greenbodies may include an activatable binder and the activatable binder may be activated prior to sintering.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S.Provisional Patent Ser. No. 61/022,952, filed on Jan. 23, 2008.

GOVERNMENT CONTRACT

The U.S. Government has a paid-up license in this invention and theright in limited circumstances to require the patent owner to licenseothers on reasonable terms as provided for by the terms of contract No.DE-FC26-05NT42644 awarded by the Department of Energy.

FIELD OF THE INVENTION

The present invention relates to the field of metallurgy, and, moreparticularly, to methods of making a combustion turbine component from aplurality of metallic combustion turbine subcomponent greenbodies.

BACKGROUND OF THE INVENTION

A combustion turbine typically includes, in a serial flow relationship,a compressor section to compress the entering airflow, a combustionsection in which a mixture of fuel and the compressed air is burned togenerate a propulsive gas flow, and a turbine section that is rotated bythe propulsive gas flow. After passing through the turbine section, thepropulsive gas flow exits the engine through a diffuser section. Inground based combustion turbines used for electricity generation, poweris normally extracted from the rotating shaft to drive an electricalpower generator.

A component of such a combustion turbine may advantageously be preciselyformed and may take a variety of complicated shapes. Some currentmethods of combustion turbine component formation include casting andforging.

Casting is a manufacturing process by which a liquid metal is pouredinto a mold, typically ceramic, which contains a hollow cavity of thedesired shape to be formed. The liquid metal is allowed to solidify andthe solid combustion turbine component casting is then ejected or brokenout of the mold to complete the process. There may, however, belimitations on the size of the combustion turbine components that may beformed by casting. Likewise, there may be limitations on the size ofsurface features of the combustion turbine components that may be formed(e.g. it may not be possible to form surface features having dimensionsbelow a certain size).

Forging is the term for shaping metal by using localized compressiveforces. A combustion turbine component formed by forging may berelatively strong and may have a fine grain structure. However, due tothe fine grain structure, a forged combustion turbine componentgenerally exhibits relatively low resistance to creep and may thus beunsuitable for use in certain applications Subsequent heat treatment canpromote grain growth, however, and it is may be easier to control grainsize in a forging than a casting. In addition, the formation of smallsurface features on such a combustion turbine component during theforging process may be difficult. Since forgings are generally solidshapes and cooling passages are later machined into the forging, it maybe difficult to machine fine scale internal features on an internalsurface of a cooling passage of a forging.

As discussed above, due to process limitations and cost concerns,forming an entire combustion turbine component of a desired shape andhaving desired surface features by the above processes may be difficultor costly. Thus, attempts at forming combustion turbine subcomponentsand joining the subcomponents together to form a whole combustionturbine component have been made.

Some efforts have focused on welding. U.S. Pat. No. 7,337,940 toSubramanian et al., for example, discloses a method of manufacturing acombustion turbine component by friction stir welding a plurality ofcombustion turbine subcomponents together. The combustion turbinesubcomponents are formed by conventional processes, such as casting orforging. However, some features may not be easily or cost effectivelyformed by casting or forging processes. In addition, some combustionturbine subcomponents may be constructed from materials that are noteasily friction stir welded.

Other efforts at joining combustion turbine subcomponents together toform a combustion turbine component have instead focused on brazing.U.S. Pat. No. 6,434,946 to Shaw et al. discloses a method of making acombustion turbine component by bonding a brazing alloy to the surfacesof two combustion turbine subcomponents to be joined together andassembling the two combustion turbine subcomponents. The assembly isthen heated to a brazing temperature to form a braze joint between thecombustion turbine subcomponents, thereby forming the combustion turbinecomponent. However, a braze joint may be undesirable in some situationsand may not provide as strong a bond as desired.

In addition, the continuing effort to design and build more powerful andefficient combustion turbines has led to a desire for a componentthereof to have enhanced high performance capabilities, such as heattransfer. Indeed, a component's ability to transfer heat away fromitself is particularly important due to the high operating temperaturesof combustion turbines.

Newton's Law of Cooling states that the rate of heat loss of a body isproportional to both the difference in temperatures between the bodyitself and its environment and the surface area of the body. Therefore,one way to enhance the cooling capabilities of a combustion turbinecomponent is to increase its surface area.

U.S. Pat. Pub. 2008/0000611 to Bunker at al., for example, discloses amethod of forming a casting mold that will be used to cast a combustionturbine component having a variety of surface cooling features, such ashemispheres, that increase the surface area of the combustion turbinecomponent. The increased surface area provides the combustion turbinecomponent with enhanced cooling capabilities. However, a combustionturbine component formed by casting and having an increased surface areamay not be desirable in some applications. Furthermore, certainarrangements of surface cooling features may not be easily formed bycasting techniques.

U.S. Pat. No. 6,503,574 to Skelly et al. discloses a method for making acombustion turbine component having cooling grooves defined therein. Acombustion turbine component substrate is formed by single crystalcasting techniques and then a bond coating is formed on the combustionturbine component substrate. A pattern of three-dimensional recessedgrooves is etched in the bond coating by photolithography and then athermal barrier coating is formed on the bond coating. However, recessedgrooves may not provide the desired cooling capabilities in someapplications.

Therefore, different methods of joining combustion turbine subcomponentstogether to form a combustion turbine component may be desirable. Inaddition, a combustion turbine component having increased surface areathat is formed by joining a plurality of combustion turbinesubcomponents together may also be desirable.

SUMMARY OF THE INVENTION

In view of the foregoing background, it is therefore an object of thepresent invention to provide a method of making a combustion turbinecomponent by joining a plurality of combustion turbine subcomponentstogether.

This and other objects, features, and advantages in accordance with thepresent invention are provided by a method of making a combustionturbine component that may comprise assembling a plurality of metalliccombustion turbine subcomponent greenbodies together to form a metallicgreenbody assembly, and sintering the metallic greenbody assembly tothereby form the combustion turbine component. The assembling andsintering of the plurality of metallic combustion turbine subcomponentgreenbodies to form the combustion turbine component may provide forbetter tolerance and shrinkage control of the resulting combustionturbine component than possible if finished combustion turbinesubcomponents were assembled and joined together. In addition, thismethod advantageously provides a stronger bond between the plurality ofmetallic combustion turbine subcomponent greenbodies.

Each of the plurality of metallic combustion turbine subcomponentgreenbodies may be formed by direct metal fabrication (DMF). The DMF maycomprise tomo lithographic molding. The DMF may also comprise metalinjection molding. DMF advantageously allows for a greater variety ofshapes to be formed than casting or forging. In addition, DMF allows theformation of smaller surface features than may be possible withconventional casting or forging processes.

Each of the plurality of metallic combustion turbine subcomponentgreenbodies may comprise an activatable binder. Additionally oralternatively, the activatable binder may be positioned between adjacentones of the plurality of metallic combustion turbine subcomponentgreenbodies. The activatable binder may be activated prior to sintering.

The combustion turbine component may be devoid of interfaces betweenadjacent ones of the plurality of metallic combustion turbinesubcomponent greenbodies. Alternatively, the combustion turbinecomponent may have interfaces between adjacent ones of the plurality ofmetallic combustion turbine subcomponent greenbodies.

Each of the plurality of metallic combustion turbine subcomponentgreenbodies may comprise at least one of an oxide dispersionstrengthened (ODS) alloy, an intermetallic compound, and a refractorymetal. Such materials may be unusable with a conventional casting orforging process and may impart the combustion turbine component withvarious desirable properties.

At least one of the plurality of metallic combustion turbinesubcomponent greenbodies may be formed to have a plurality of surfacefeatures, each with a dimension less than 200 μm. These surface featuresmay provide the combustion turbine component with enhanced heatdissipation properties and high temperature resistance by increasing thesurface area thereof. A large number of such small surface features mayincrease the surface area beyond what would be possible with largersurface features alone.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart for a method of forming a combustion turbinecomponent in accordance with the present invention.

FIG. 2 is a more detailed flowchart for the method of forming acombustion turbine component in accordance with the present invention.

FIG. 3 is another more detailed flowchart for the method of forming acombustion turbine component in accordance with the present invention.

FIG. 4 is a yet another flowchart for the method of forming a combustionturbine component in accordance with the present invention.

FIG. 5 is a cross sectional view of combustion turbine component havinga plurality of surface cooling features in accordance with the presentinvention.

FIG. 6 is a greatly enlarged perspective view of the one of the surfacecooling features of the combustion turbine component of FIG. 5.

FIG. 7 is a greatly enlarged perspective view of an alternativeembodiment of a surface cooling feature for a combustion turbinecomponent in accordance with the present invention.

FIG. 8 is a greatly enlarged schematic cross sectional view of yetanother surface cooling feature for a combustion turbine component inaccordance with the present invention.

FIG. 9 is a greatly enlarged schematic cross sectional view of stillanother surface cooling feature for a combustion turbine component inaccordance with the present invention.

FIG. 10 is a greatly enlarged schematic cross sectional view of anothersurface cooling feature for a combustion turbine component in accordancewith the present invention.

FIG. 11 is a greatly enlarged cross schematic sectional view of stillanother surface cooling feature for a combustion turbine component inaccordance with the present invention.

FIG. 12 is flowchart of a method of forming a combustion turbinecomponent having a plurality of surface cooling features in accordancewith the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which preferred embodimentsof the invention are shown. This invention may, however, be embodied inmany different forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. Likenumbers refer to like elements throughout.

Referring initially to the flowchart 14 of FIG. 1, a first embodiment ofa method of making a combustion turbine component is now described.After the start (Block 15), at Block 16 a plurality of metalliccombustion turbine subcomponent greenbodies are assembled together toform a metallic greenbody assembly. The metallic greenbody assembly hasa shape closely resembling that of the final combustion turbinecomponent, but has a greater porosity, a lesser density, and a largersize. The plurality of metallic combustion turbine subcomponentgreenbodies may be assembled by conventional methods known to those ofskill in the art.

Those of skill in the art will understand that a metallic combustionturbine subcomponent greenbody is an unsintered metallic combustionturbine subcomponent that lacks strength and has both a low density andhigh porosity compared to a sintered metallic body.

At Block 17, the metallic greenbody assembly is sintered to thereby formthe combustion turbine component. During sintering, the metallicgreenbody assembly may shrink in all directions by up to 20%, therebyincreasing in density. In addition, the porosity of the metallicgreenbody assembly is reduced and the strength of the metallic greenbodyassembly is increased.

The sintering may be solid state sintering or liquid state sintering.During solid state sintering, the metallic greenbody assembly is heatedto a temperature below the melting point of its constituents and held atthat temperature until its particles adhere to each other. During liquidstate sintering, the metallic greenbody assembly is heated until atleast one but not all of its constituents melt and reach a liquid state.

The metallic greenbody assembly may be placed under pressure during thesintering. In this case, the sintering may comprise hot isostaticpressing (HIP). HIP subjects a component to high gas pressure in acontainment vessel. The pressurizing gas is preferably argon, althoughother inert gasses may be used as will be appreciated by those of skillin the art. The pressurizing gas is preferably applied between 100 and310 MPa (15,000 p.s.i. and 45,000 p.s.i.) at a temperature of 480° C. to2000° C., although other pressures and other temperatures may be used aswell. As the containment vessel is heated during the HIP, the pressureinside increases. The pressure is isostatic because it is applied to themetallic greenbody assembly from all directions evenly. The pressure andheat during HIP helps to reduce internal voids in the metallic greenbodyassembly through a combination of plastic deformation, creep, anddiffusion bonding, thus increasing the density of the metallic greenbodyassembly. Alternatively, the sintering may be performed without themetallic greenbody assembly being placed under pressure. Block 18indicates the end of the method.

After sintering, a bond coating may be formed on the combustion turbinecomponent and a thermal barrier coating may be formed on the bondcoating. Any number of exemplary bond coatings and thermal barriercoatings known to those of skill in the art may be used. In addition,the thermal barrier coating may be formed directly on the combustionturbine component, without an intervening bond coating. Additionally oralternatively, a wear resistant layer may be formed on the combustionturbine component.

Those of skill in the art will understand that, in some embodiments,after sintering the combustion turbine component may be placed into acasting mold and that additional metallic layers may therefore be formedaround the combustion turbine component, encasing it.

In addition, it should be understood that a plurality of metalliccombustion turbine subcomponent greenbodies may be assembled to form ametallic greenbody assembly and that the metallic greenbody assembly maybe sintered to form a combustion turbine subcomponent assembly. Multiplecombustion turbine subcomponent assemblies may be formed in this fashionand then joined together by conventional methods, such as welding orbrazing, to form the combustion turbine component. The multiplecombustion turbine subcomponent assemblies may also be placed into acasting mold and additional layers may be formed therearound to form acombustion turbine component

Referring now to the flowchart 20 of FIG. 2, a more detailed method ofmaking a combustion turbine component is now described. After the start(Block 21) at Block 22 a plurality of metallic combustion turbinesubcomponent greenbodies are formed by direct metal fabrication (DMF).

Direct metal fabrication processes include (1) layered powder build-upprocesses, such as selective laser sintering (SLS), (2) processes usinglight energy to chemically change a material, such as stereolithography(SLA), (3) deposition techniques that selectively deposit eitherparticles or thin laminates, such as solid ground curing (SGC),laminated object manufacturing (LOM), fused deposition modeling (FDM),and ballistic particle manufacturing (BPM), and (4) powder metallurgyprocesses that tightly compact a metal powder into a mold or die, suchas metal injection molding (MIM) or tomo lithographic molding. SLS, forexample, uses a high powered laser to fuse the particles of a metalpowder into a mass representing a desired three dimensional object, onelayer at a time.

The plurality of metallic combustion turbine subcomponent greenbodiesmay be formed by any of the above DMF processes, or by other processesknown to those of skill in the art. In addition, each of the pluralityof metallic combustion turbine subcomponent greenbodies may be formed bythe same DMF process, or each may be formed by different DMF processes.For example, it may be advantageous for some of the metallic combustionturbine subcomponent greenbodies to be formed by SLA while others areformed by MIM.

Each of the plurality of metallic combustion turbine subcomponentgreenbodies in this embodiment may comprise an activatable binder and atleast one of an oxide dispersion strengthened (ODS) alloy, anintermetallic compound, and a refractory metal. Each of the plurality ofmetallic combustion turbine subcomponent greenbodies may also comprise aNickel based superalloy and, optionally, at least one rare earthelement. The activatable binder may comprise a polymer or plasticbinder, a metallic mix including a melting point depressor, or anothersuitable binder known to those of skill in the art. Intermetalliccompounds are solid phases containing two or more metallic elements,optionally having one or more non-metallic elements. Intermetallicphases form due to strong bonding between unlike metal atoms, thisresults in an ordered crystal structure, whereby the various atomicspecies occupy specific sublatice sites. Intermetallic compounds mayalso include interstitial compounds such as carbides and nitrides. Suchintermetallic compounds offer advantageous properties like hightemperature resistance and hardness. Refractory metals include tungsten,molybdenum, niobium, tantalum, and rhenium, and are extraordinarilyresistant to heat and wear. The methods described herein allow theformation of combustion turbine components from the above materials,whereas conventional methods such as casting and forging may not. Itshould be noted that the plurality of metallic combustion turbinesubcomponent greenbodies may be metallic and not contain any ceramic.

At Block 23, the plurality of metallic combustion turbine subcomponentgreenbodies are assembled together to form a metallic greenbodyassembly. At Block 24, the activatable binder is activated. Theactivatable binder may be activated by heating the greenbody assembly,or may be activated by other suitable methods. After activation, theactivatable binder may optionally be cured through the use of a chemicalagent, ultraviolet radiation, bombardment with an electron beam, orfurther heating. Furthermore, the activatable binder may optionally beremoved from the greenbody assembly by a pre-sintering heat treating ata temperature of 400° C. to 600° C., or at other suitable temperatures,or through the use of chemical agents. This pre-sintering heat treating,in some embodiments, may increase the density, decrease the porosity,and shrink the greenbody assembly.

At Block 25, the metallic greenbody assembly is sintered to thereby formthe combustion turbine component. Block 26 indicates the end of themethod.

With reference to the flowchart 30 of FIG. 3, an alternative embodimentof a method of making a combustion turbine component is now described.After the start (Block 32), at Block 34, a plurality of metalliccombustion turbine subcomponent greenbodies is formed by tomolithographic molding. Tomo lithographic molding involves the productionof a master tool which is then used either directly as a mold or die, oralternatively used to produce a secondary consumable mold. To create themaster tool, a series of layers are fabricated with lithographictechniques. The layers are micro-machined to add additional features anddetails, and are then laminated together by brazing or epoxy bonding toform the master tool. The master tool may then be used as a mold or diefor processes such as microcasting, microinjection molding, metalinjection molding, and powder injection molding.

It should be understood that the term tomo lithographic molding as usedhereinafter is to mean the use of a master tool formed by tomolithographic molding in conjunction with a suitable process to formmetallic combustion turbine subcomponent greenbodies therefrom.

At Block 36, the plurality of metallic combustion turbine subcomponentgreenbodies is assembled together and an activatable binder ispositioned between adjacent ones of the plurality of metallic combustionturbine subcomponent greenbodies to form a metallic greenbody assembly.The activatable binder may be formed from the same material as theplurality of metallic combustion turbine subcomponent greenbodies thathas been mixed with a suitable binding agent, such as a polymer orplastic binder or a melting point depressor, such as boron.Alternatively, the activatable binder may be a metallic mix togetherwith a melting point depressor.

If the activatable binder includes a melting point depressor, thesintering may be liquid state sintering and the plurality of metalliccombustion turbine subcomponent greenbodies may bond together bytransient liquid phase (TLP) bonding. If the plurality of metalliccombustion turbine subcomponent greenbodies is to be bonded together byTLP bonding, the activatable binder between each of the plurality ofmetallic combustion turbine subcomponent greenbodies is considered to bea TLP forming layer. The metallic greenbody assembly and thus the TLPforming layer are then heat treated at a temperature higher than themelting point of the TLP forming layer, but lower than the melting pointof the other constituents of the metallic greenbody assembly.Accordingly, the TLP forming layer melts during the sintering.

As the temperature remains constant, the melting point depressordiffuses from the TLP forming layer into each of the plurality ofmetallic combustion turbine subcomponent greenbodies, and molecules fromeach of the plurality of metallic combustion turbine subcomponentgreenbodies diffuse into the TLP layer. As a result of this diffusion,the melting point of TLP layer increases beyond the temperature of theheat treatment and the TLP layer, now close in composition to theplurality of metallic combustion turbine subcomponent greenbodies,resolidifies. The resulting bonded region between each of the pluralityof metallic combustion turbine subcomponent greenbodies is thin and of ahigh strength.

Those of skill in the art will appreciate that the activatable bindermay be positioned between certain adjacent ones of the plurality ofmetallic combustion turbine subcomponent greenbodies but not betweenother adjacent ones of the plurality of metallic combustion turbinesubcomponent greenbodies.

At Block 38, the activatable binder is activated. At Block 40, themetallic greenbody assembly is sintered to thereby form the combustionturbine component. The combustion turbine component is devoid of aninterface between adjacent ones of the plurality of metallic combustionturbine subcomponent greenbodies after sintering. This lack ofinterfaces may provide the combustion turbine component with increasedstrength and the metallurgical properties throughout may be consistent.Block 42 indicates the end of the method.

Another embodiment of a method of making a combustion turbine componentis now described with reference to the flowchart 50 of FIG. 4. After thestart (Block 52), at Block 54 a plurality of metallic combustion turbinesubcomponent greenbodies is formed by metal injection molding. Metalinjection molding involves injecting a metallic powder and a suitablebinder into a mold, in some situations with conventional plasticinjection molding machines and processes. The mold used with the metalinjection molding may be formed by tomo lithographic molding or may beformed from other methods.

At least one of the plurality of metallic combustion turbinesubcomponent greenbodies is formed to have at least one internal coolingpassage. This internal cooling passage is formed to have a plurality ofinternal surface features, each with a dimension less than 200 μm. Aswill be explained in detail below, this plurality of internal surfacefeatures increases the internal surface area of the cooling passages ofthe combustion turbine component and therefore enhances its ability totransfer heat away from itself. As will also be explained in detailbelow, each of the plurality of internal surface features may take avariety of shapes and may be either a projection or a recess.

Of course, those of skill in the art will recognize that, in someapplications, one of the metallic combustion turbine subcomponentgreenbodies need not have internal cooling passages. In suchapplications, the surface features described herein may be externalcooling features.

At Block 56, the plurality of metallic combustion turbine subcomponentgreenbodies is assembled together to form a metallic greenbody assembly.At Block 58, the metallic greenbody assembly is sintered to thereby formthe combustion turbine component. In this embodiment, the combustionturbine component has interfaces between adjacent ones of the pluralityof metallic combustion turbine subcomponent greenbodies. Block 60indicates the end of the method. Those of skill in the art willappreciate that, in some applications, there may be an interface betweencertain adjacent ones of the plurality of metallic combustion turbinesubcomponent greenbodies after sintering and no interface between otheradjacent ones of the plurality of metallic combustion turbinesubcomponent greenbodies after sintering.

With reference to FIGS. 5-6, a combustion turbine component 70 having aplurality of internal surface cooling features 72 is now described. Thecombustion turbine component 70 comprises a metallic body 71 to defineat least a substrate for the combustion turbine component, the metallicbody having a plurality of internal cooling passages 73. The internalcooling passages 73 each have an internal surface portion 75.

The internal surface portion 75 defines a plurality of coarse surfacecooling features 74, each having a dimension greater than 500 μm. Asperhaps best shown in FIG. 6, one of the plurality of coarse surfacecooling features 74 illustratively comprises a three-tiered projection.

A plurality of fine surface cooling features 76 is on at least one ofplurality of coarse surface cooling features 74, each having a dimensionless than 200 μm. As also shown in FIG. 6, the plurality of fine surfacecooling features 76 illustratively comprises convex or hemisphericalprojections, and may be on the order of 50 μm, for example.

The surface cooling features described herein increase the surface areaof the internal surface portion 75 of the combustion turbine component70, thereby enhancing its ability to transfer heat away from itself andcool itself and into a cooling fluid flowing therethrough. This enhancedheat transfer may allow for the size of the cooling passageways 73 to bedecreased compared to those of conventional combustion turbinecomponents. Furthermore, this enhanced heat transfer may allow for anamount of cooling fluid used to cool the combustion turbine component 70to be reduced.

A first additional surface cooling feature 77 comprising an “x” shapedprojection is illustratively on the coarse surface cooling feature 74and has a dimension greater than 200 μm. It should be understood that,although one first additional cooling feature 77 is shown, there mayinstead be a plurality of first additional surface cooling features onat least one of the plurality of coarse surface cooling features 74 andthat ones of this plurality of first additional surface cooling featuresmay be of sizes both greater than and less than 200 μm.

A second additional surface cooling feature 78 comprising acircular-base pin and having a dimension less than 200 μm isillustratively on the first additional surface cooling feature 77.

Those of skill in the art will recognize that there may be any number ofstacked pluralities of surface cooling features (e.g. there may be athird plurality of additional surface cooling features on the secondplurality of additional surface cooling features, and so on and soforth).

Each of the plurality of coarse surface cooling features 74, pluralityof fine surface cooling features 76, first additional plurality ofsurface cooling features 77, and second additional plurality of surfacecooling features 78 may be projections of other suitable shapes,including but not limited to square-base pins, circular-base pins,square-base pyramids, circular base cones, tapered pins, polygonal-basedpyramids, conical frustums, pyramidical frustums, convex cones,serpentine ribs, hemispheres, and combinations thereof. Each of theplurality of coarse surface cooling features 74, plurality of finesurface cooling features 76, first additional plurality of surfacecooling features 77, and second additional plurality of surface coolingfeatures 78 may also be recesses of various shapes, including but notlimited to concave cones, dimples, concave hemispheres, serpentine ribs,square shaped recesses, circular shaped pin recesses, and combinationsthereof. Each of the plurality of coarse surface cooling features 74,plurality of fine surface cooling features 76, first additionalplurality of surface cooling features 77, and second additionalplurality of surface cooling features 78 may have the same shape, oreach may have a different shape. For example, one of the plurality offine surface cooling features 76 may be a convex hemisphericalprojection while another of the plurality of fine surface coolingfeatures may be a concave square shaped recess.

The metallic combustion turbine component body 70 may comprise at leastone of an oxide dispersion strengthened (ODS) alloy, an intermetalliccompound, and a refractory metal. Advantages of construction from thesematerials are explained above. In addition, the metallic body 71 maycomprise a plurality of metallic combustion turbine subcomponent bodiesbonded together, or a plurality of metallic combustion turbinesubcomponent greenbodies bonded together, by methods described in detailabove.

An alternative embodiment of the surface cooling features in accordancewith the present invention will now be described with reference to FIG.7. One of a plurality of coarse surface cooling features 82 comprising arectangular projection has a dimension greater than 500 μm, and aplurality of fine surface cooling features 86 comprising rectangularprojections and having at least one dimension less than 200 μm isillustratively thereon. A first plurality of additional surface coolingfeatures 84 comprising convex hemispheres and having at least onedimension less than 200 μm, such as less than 50 μm, is on the pluralityof fine surface cooling features 86.

Various embodiments of the such surface cooling features in accordancewith the present invention will now be described with reference to FIGS.8-11. Referring first to FIG. 8, an internal surface portion of acooling passage of an combustion turbine component 88 defines aplurality of coarse surface cooling features 90 comprising rectangularprojections having a dimension, in this instance the width, that isgreater than 500 μm. A plurality of fine surface cooling features 92comprising hemispherical projections and having a dimension, in thisinstance a diameter, that is less than 200 μm is on the plurality ofcoarse surface cooling features 90.

Referring now to FIG. 9, an internal surface portion of a coolingpassage of a combustion turbine component 94 defines a plurality ofcoarse surface cooling features 96 comprising rectangular recesseshaving a dimension greater than 500 μm. A plurality of fine surfacecooling features 98 comprising concave hemispherical recesses having adimension less than 200 μm is defined in the plurality of coarse surfacecooling features 98.

Illustrated in FIG. 10 is an internal surface portion of a coolingpassage of an combustion turbine component 100 defining a plurality ofcoarse surface cooling features 102 comprising rectangular projectionshaving a dimension greater than 500 μm. A plurality of fine surfacecooling features 104 comprising concave hemispherical recesses having adimension less than 200 μm is defined in the plurality of coarse surfacecooling features 102.

Now referring to FIG. 11, an internal surface portion of a coolingpassage of a combustion turbine component 106 defines a plurality ofcoarse surface cooling features 108 comprising rectangular recesseshaving a dimension greater than 500 μm. A plurality of fine surfacecooling features 110 comprising convex hemispheres and having adimension less than 200 μm is on the plurality of coarse surface coolingfeatures 108.

A method of making a combustion turbine component having a plurality ofsurface cooling features is now described. The method includes forming ametallic combustion turbine component body by direct metal fabrication(DMF). The metallic combustion turbine component body is formed to haveat least one surface portion defining a plurality of coarse surfacecooling features each having a first dimension. The metallic combustionturbine component body is also formed to have at least one fine coolingfeature on at least one of the first plurality of surface coolingfeatures and having a second dimension less than 200 μm.

The first dimension may be greater than 500 μm. There may be a pluralityof fine surface cooling features on one of the plurality of coarsesurface cooling features, or there may be a plurality of fine surfacecooling features on each of the plurality of coarse surface coolingfeatures.

The at least one fine surface cooling feature may comprise a projectionor a convex projection. Alternatively, the at least one fine surfacecooling feature may comprise a recess or a concave recess. If there area plurality of fine surface cooling features, each of the plurality offine surface cooling features may comprise the same shape, or maycomprise different shapes (e.g. one of the plurality of fine surfacecooling features may comprise a convex projection while another of theplurality of fine surface cooling features may comprise a concaverecess).

One of the plurality of coarse surface cooling features may comprise aprojection or a convex projection. In addition, one of the plurality ofcoarse surface cooling features may comprise a recess or a concaverecess. Each of the plurality of coarse cooling features may be the sameshape or each may be a different shape.

Additional details of the plurality of coarse surface cooling featuresand the at least one fine surface cooling feature may be found above.The DMF may comprise tomo lithographic molding or metal injectionmolding, details of which may also be found above.

The metallic body may comprise at least one of an oxide dispersionstrengthened (ODS) alloy, an intermetallic compound, and a refractorymetal. Advantageous properties of these materials are discussed above.The metallic body may additionally or alternatively comprise a nickelbased superalloy and, optionally, at least one rare earth element.

With reference to the flowchart 120 of FIG. 12, a more detailed methodof forming a combustion turbine component having surface coolingfeatures is now described. After the start (Block 122), at Block 124 aplurality of metallic combustion turbine subcomponent greenbodies areformed by direct metal fabrication (DMF). At least one of the pluralityof metallic combustion turbine subcomponent greenbodies is formed tohave at least one surface portion defining a plurality of coarse surfacecooling features each having a first dimension. In addition, the atleast one of the plurality of metallic combustion turbine subcomponentgreenbodies is formed to have at least one fine surface cooling featureon at least one of the plurality of coarse surface cooling features andhaving a dimension less than the first dimension and less than 200 μm.

The plurality of metallic combustion turbine subcomponent greenbodiesmay comprise an activatable binder. The activatable binder may beactivated prior to sintering.

At Block 126, the plurality of metallic combustion turbine subcomponentgreenbodies are assembled together to form a metallic greenbodyassembly. At Block 128, the metallic greenbody assembly is sintered tothereby form the metallic body. Block 130 indicates the end of themethod. Further details of assembling and sintering may be found above.

Many modifications and other embodiments of the invention will come tothe mind of one skilled in the art having the benefit of the teachingspresented in the foregoing descriptions and the associated drawings.Therefore, it is understood that the invention is not to be limited tothe specific embodiments disclosed, and that modifications andembodiments are intended to be included within the scope of the appendedclaims.

What is claimed is:
 1. A method comprising: liquid state sintering ametallic greenbody assembly to form a combustion turbine component;wherein: the metallic greenbody assembly comprises a plurality ofmetallic combustion turbine subcomponent greenbodies and a binder; thebinder located between adjacent ones of the plurality of metalliccombustion turbine subcomponent greenbodies; the binder comprising ametallic mix and a melting point depressor; the binder activatable tocause liquid phase bonding between the plurality of metallic combustionturbine subcomponent greenbodies; at least one metallic combustionturbine subcomponent greenbody from the plurality of metallic combustionturbine subcomponent greenbodies was formed via tomo lithographicmolding; and at least one metallic combustion turbine subcomponentgreenbody from the plurality of metallic combustion turbine subcomponentgreenbodies was formed via a direct metal fabrication process selectedfrom a layered powder buildup, selective laser sintering,stereolithography, deposition, solid ground curing, laminated objectmanufacturing, fused deposition, and ballistic particle manufacturing.2. The method of claim 1, further comprising: forming at least onemetallic combustion turbine subcomponent greenbody from the plurality ofmetallic combustion turbine subcomponent greenbodies.
 3. The method ofclaim 1, further comprising: assembling the plurality of metalliccombustion turbine subcomponent greenbodies to form the metallicgreenbody assembly.
 4. The method of claim 1, further comprising: priorto said sintering, activating the binder.
 5. The method of claim 1,further comprising: positioning the binder between the adjacent ones ofthe plurality of metallic combustion turbine subcomponent greenbodies.6. The method of claim 1, wherein: each of the plurality of metalliccombustion turbine subcomponent greenbodies comprises the binder
 7. Themethod of claim 1, wherein: after said sintering, the combustion turbinecomponent is devoid of interfaces between adjacent ones of the pluralityof metallic combustion turbine subcomponent greenbodies.
 8. The methodof claim 1, wherein: after said sintering, the combustion turbinecomponent has interfaces between adjacent ones of the plurality ofmetallic combustion turbine subcomponent greenbodies.
 9. The method ofclaim 1, wherein: each of the plurality of metallic combustion turbinesubcomponent greenbodies comprises at least one of an oxide dispersionstrengthened (ODS) alloy, an intermetallic compound, and a refractorymetal.
 10. The method of claim 1, wherein: a metallic combustion turbinesubcomponent greenbody from the plurality of metallic combustion turbinesubcomponent greenbodies comprises an oxide dispersion strengthened(ODS) alloy.
 11. The method of claim 1, wherein: a metallic combustionturbine subcomponent greenbody from the plurality of metallic combustionturbine subcomponent greenbodies comprises an intermetallic compound.12. The method of claim 1, wherein: a metallic combustion turbinesubcomponent greenbody from the plurality of metallic combustion turbinesubcomponent greenbodies comprises a refractory metal.
 13. The method ofclaim 1, wherein: at least one metallic combustion turbine subcomponentgreenbody from the plurality of metallic combustion turbine subcomponentgreenbodies has a plurality of surface features each with a dimensionless than 200 μm.
 14. The method of claim 1, wherein: the direct metalfabrication process comprises a layered powder buildup process.
 15. Themethod of claim 1, wherein: the direct metal fabrication processcomprises selective laser sintering.
 16. The method of claim 1, wherein:the direct metal fabrication process comprises stereolithography. 17.The method of claim 1, wherein: the direct metal fabrication processcomprises a deposition technique.
 18. The method of claim 1, wherein:the direct metal fabrication process comprises solid ground curing. 19.The method of claim 1, wherein: the direct metal fabrication processcomprises laminated object manufacturing.
 20. The method of claim 1,wherein: the direct metal fabrication process comprises fused depositionmodeling.
 21. The method of claim 1, wherein: the direct metalfabrication process comprises ballistic particle manufacturing.
 22. Amethod comprising: assembling a plurality of metallic combustion turbinesubcomponent greenbodies and a binder to form a metallic greenbodyassembly; positioning the binder between adjacent ones of the pluralityof metallic combustion turbine subcomponent greenbodies; activating thebinder; and sintering the metallic greenbody assembly to form acombustion turbine component; wherein: the binder located betweenadjacent ones of the plurality of metallic combustion turbinesubcomponent greenbodies; the binder comprising a metallic mix and amelting point depressor; the binder activatable to cause liquid phasebonding between the plurality of metallic combustion turbinesubcomponent greenbodies; at least one metallic combustion turbinesubcomponent greenbody from the plurality of metallic combustion turbinesubcomponent greenbodies was formed via tomo lithographic molding; andat least one metallic combustion turbine subcomponent greenbody from theplurality of metallic combustion turbine subcomponent greenbodies wasformed via a direct metal fabrication process selected from a layeredpowder buildup, selective laser sintering, stereolithography,deposition, solid ground curing, laminated object manufacturing, fuseddeposition, and ballistic particle manufacturing.